Spark plug



Nov 8, 1949 R. J. L. DUTTERER 2 S PARK PLUG Filed June 24, 1946 IN V EN TOR.

a f 564 UTA5pUf/L6/1W Patented Nov. 8, 1949 SPARK PLUG Rex J. L. Dutterer, Hastings, Mich., assignor to Hastings Manufacturing M ich.

Company, Hastings,

Application June 24, 1946, Serial No. 678,829 5 Claims. (Cl. 1231.69)

This invention relates to improvements in spark plug.

The principal First,

production methods.

Second, to provide effective means for conducting heat away from the electrode of a spark plug.

Third, to provide a spark plug with both an efiicient heat dissipating characteristic and a positive seal around the electrode.

Fourth, to provide an effective seal for the center electrode of a spark plug which may be applied without requiring a second cleaning process to remove excess sealing material.

Fifth, to provide a seal for the center electrode of a spark plug which is both effective and inexpensive.

The drawings, of which there is one sheet illustrate a preferred form of the invention.

Fig. 1 is a vertical cross-sectional view through a spark plug embodying the invention.

Fig. 2 is an enlarged fragmentary cross-sectional view showing the details of construction of the seal in the center of the spark plug.

In the drawings, the reference character I indicates a porcelain or ceramic insulator which is formed with a central bore 2 and the sloping exterior shouldered portion 3. The bore 2 is provided with a threaded section 4 near the middle thereof and a lower portion 5 of reduced cross section.

The shouldered portion 3 of the insulator is arranged to fit within the sleeve member 6 and be sealed therein by folding over the rim 7 of the sleeve to clamp the gaskets 8 tightly against the shouldered portion. The sleeve 6 is provided with the usual hex nut shaped body 9 and threaded lower portion I 0 for installing the spark plug in an engine. An external electrode II is secured to the sleeve Ill.

The central bore 2 receives the upper electrode I 2 which is threaded at E2! into the threaded portion 4 of the bore and is provided at its upper rests upon the shoulder !6 of the lower electrode H. The shoulder 16 of the central bore at the upper end of the re duced portion 5. The spring is made of heat and corrosion resistant metal and gives a complete metallic path between the two electrodes.

A mixture of cement and finely divided metal powder is packed around the upper end of the as the heating effect of the current through it to cause the spark.

It will be noted that the mixture of cement broken by unequal expansion It should be The insulating and the upper ous metal connection between lower electrodes for the passage of current therethrough.

The lower mixture of cement and metal serves to conduct heat away of cement will eifectively seal the spark plug the center electrodes.

spark plugs.

Since the cement is introduced through the bore 2 before the upper electrode 12 is installed and after the lower portion of the bore is closed .by the lower electrode,

there is little tendency for the cement to escape along the lower electrode and require that the spark plug be passed through a cleaning operation after assembly. The elimination of the cleaning and heating steps will materially reduce the cost of manufacture of the spark plug.

The invention has been illustrated and described in a highly satisfactory embodiment thereof. No attempt has been made to show other possible adaptations, as it is believed that this disclosure will enable those skilled in the art to adapt or embody the invention as may be desired.

Having thus claim as new and Patent is:

1. A spark plug comprising an insulating member having an enlarged exterior portion and defining a central bore having an internally threaded section intermediate of the ends thereof within said enlarged portion and a lower portion of reduced cross section spaced below said threaded portion, a lower electrode having a shoulder thereon intermediate of its ends, said lower electrode being positioned in said reduced section of said bore with its shoulder engaging the lower end of the upper portion of said bore, an upper electrode extending into said bore from the top thereof and having a threaded connection with the upper part of the threaded section of said bore, a-coil spring positioned. in said bore and extending between the shoulder of said lower electrode and the end of said upper electrode, a mixture of cement and powdered metal packed in said bore around the upper end of said lower electrode and a mixture of insulating cement positioned in said bore on top of said first mixture and filling the remainder of said bore to around the lower end of said upper electrode, said insulating cement having approximately the same coefficient of expansion as said insulating member.

2. A spark plug comprising an insulating member defining a central bore having a lower portion of reduced cross section, a lower electrode having a shoulder thereon intermediate of its ends, said lower electrode being positioned in said reduced section of said bore with its shoulder engaging the lower end of the upper portion of said bore, an upper electrode extending into said bore from the topthereof, a coil spring positioned in said bore and extending between the shoulder of said lower electrode and the end of said upper electrode, a mixture of cement and powdered metal packed in said bore around the upper end of said lower electrode and a mixture of insulating cement positioned in said bore on top of said first mixture and filling the remainder of said bore to around the lower end of said upper electrode, said insulating cement in its solidified state having approximately the same coeificient of expansion as said insulating member.

3. A spark plug comprising an insulating member defining a central bore having a lower portion of reduced cross section, a lower electrode positioned in said reduced section of said bore,

described my invention, what .I desire to secure by Letters an upper electrode extending into said bore from the top thereof, and terminating above said lower electrode, a coil spring positioned in said bore and extending between said lower electrode and the end of said upper electrode, a mixture of cement and powdered metal positioned in said bore around the upper end of said lower electrode and a mixture oi ceramic cement positioned in said bore on top of saidfirst mixture and filling the remainder of said bore to around the lower end of said upper electrode, said ceramic cement in its solidified state having approximately the same coeflicient of expansion as said insulating 'member.

"4. The method of manufacturing a spark plug which comprises preparing an insulator with a central bore having a portion of reduced diameter at the bottom'thereof, dropping a lower electrode into said bore so that said electrode projects through the bottom of said bore, dropping a metallic coil spring into said bore to rest upon said lower electrode, placing a predetermined amount of intermixed ceramic cement and finely divided metal into said bore :and around the bottom of said coil spring .and the top of said lower electrode, placing a predetermined amount of ceramic cement in said bore to rest upon :the topoi.saidintermixed-cement .and metal, and introducing an upper electrode into said bore until the lowerend thereof penetrates said cement and contacts said spring, said uppermost cement in its solidified state having approximately the same coefficient of expansion as said insulator.

5. The method of manufacturing a spark plug which comprises preparing an insulator with a central bore having a portion of reduced-diameter at the bottom there0f,=andan internally threaded portion thereabove, dropping .a lower electrode with a collar thereon into said bore so that said electrode projects through the 'bottomof said bore and said collar rests 'on the shoulder at the upper end of the reduced portion of said insulator, dropping a metallic coil spring into said here to rest upon said lower electrode, placing a predetermined amount of intermixed ceramic cement and finely divided metal intosaid bore and around the bottom of said coil spring and the top of said lower electrode, placing a predetermined amount of ceramic cement in said bore to rest upon the top of said intermixed cement and metal, and screwing an upper electrode into said bore until the lower end thereof penetrates said cement and contacts said spring, said uppermost cement in its solidified state -having approximately'the same coeffic'ient of expansion as said insulator.

REX J. L. DUTTERER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

